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United States Patent |
5,682,190
|
Hirosawa
,   et al.
|
October 28, 1997
|
Ink jet head and apparatus having an air chamber for improving
performance
Abstract
An ink jet head comprises a plurality of ink liquid paths in which energy
generating elements are formed, a common liquid chamber communicated with
the plurality of ink liquid paths, and an air chamber which is
communicated with the common liquid chamber via a communication section
formed at substantially a central portion of the air chamber and which ls
formed along the longitudinal direction of the common liquid chamber. This
arrangement of the ink jet head enables air in the air chamber to act on
refilling behavior of ink in each of the ink liquid paths so that
refilling in each of the ink liquid paths is not delayed.
Inventors:
|
Hirosawa; Toshiaki (Hiratsuka, JP);
Koizumi; Yutaka (Yokohama, JP);
Moriyama; Jiro (Kawasaki, JP);
Kaneko; Mineo (Yokohama, JP);
Osada; Torachika (Yokohama, JP);
Kubota; Hidemi (Komae, JP)
|
Assignee:
|
Canon Kabushiki Kaisha (Tokyo, JP)
|
Appl. No.:
|
138032 |
Filed:
|
October 19, 1993 |
Foreign Application Priority Data
| Oct 20, 1992[JP] | 4-281461 |
| Apr 16, 1993[JP] | 5-089973 |
Current U.S. Class: |
347/94; 347/42 |
Intern'l Class: |
B41J 002/05 |
Field of Search: |
347/20,21,40,42,54,65,67,84,85,92,94
|
References Cited
U.S. Patent Documents
4403228 | Sep., 1983 | Miura et al. | 347/21.
|
4539569 | Sep., 1985 | Watanabe et al. | 347/43.
|
4578687 | Mar., 1986 | Cloutier et al. | 347/94.
|
4611219 | Sep., 1986 | Sugitani et al. | 347/40.
|
4894667 | Jan., 1990 | Moriyama | 347/68.
|
4929968 | May., 1990 | Ishikawa | 347/21.
|
4947191 | Aug., 1990 | Nozawa et al. | 347/30.
|
5006867 | Apr., 1991 | Koizumi et al. | 347/17.
|
5023630 | Jun., 1991 | Moriyama | 347/68.
|
5175567 | Dec., 1992 | Asai | 347/56.
|
5220345 | Jun., 1993 | Hirosawa | 347/85.
|
Foreign Patent Documents |
0306341 | Mar., 1989 | EP.
| |
0376922 | Jul., 1990 | EP.
| |
59-98859 | Jun., 1984 | JP | 347/94.
|
61-154947 | Jul., 1986 | JP | .
|
1-308644 | Dec., 1989 | JP | .
|
Primary Examiner: Hartary; Joseph W.
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper & Scinto
Claims
What is claimed is:
1. An ink jet head including a plurality of ink liquid paths arranged in a
side-by-side relationship in a direction of arrangement, each of said
plurality of ink liquid paths including an energy generating element for
generating energy to eject an ink, and a common liquid chamber having a
pair of ends and ink supply ports provided at both of the ends, and which
is arranged substantially parallel to the direction of arrangement of said
plurality of ink liquid paths for feeding ink to said plurality of ink
liquid paths, so as to eject the ink from a plurality of ink ejection
outlets in fluid communication with said ink liquid paths by driving the
energy generating elements, said ink jet head comprising;
an air chamber extending along an arrangement of said plurality of ink
liquid paths and communicated with said common liquid chamber by a
communication section located at a substantially central part of said
common liquid chamber, said air chamber containing a gas therein for
absorbing a pressure fluctuation propagating in the ink received in said
common liquid chamber, and a part of said air chamber that is located
adjacent to said communication section being used as an ink reserving
portion.
2. An ink jet head as claimed in claim 1, wherein said air chamber is
divided into plural segments.
3. An ink jet head as claimed in claims 1 or 2, wherein said communication
section includes a plurality of communication path walls.
4. An ink jet head as claimed in claims 1 or 2, wherein a volume of said
common liquid chamber is larger than a volume of said air chamber.
5. An ink jet head as claimed in claims 1 or 2, wherein said communication
section comprises a plurality of communication paths, each having a
cross-sectional area, and a cross-sectional area of each of said ink
liquid paths is equal to or larger than the cross-sectional area of each
of said plurality of communication paths.
6. An ink jet head as claimed in claim 2, wherein said communication
section comprises a plurality of communication paths, each having a
cross-sectional area, and a total of the cross-sectional areas of said
communication paths defining said communication section is greater than a
value obtained by converting a total quantity of ink simultaneously
ejected from all of said plurality of ink ejection outlets into an area.
7. An ink jet head as claimed in claims 1 or 2, wherein said communication
section comprises a plurality of communication paths, each having a
cross-sectional area, and a total of the cross-sectional areas of said
communication paths defining said communication section is equal to at
least 1/10 of said total cross-sectional area of said ink liquid paths.
8. An ink jet head as claimed in claims 1 or 2, wherein said ink ejection
outlets are arranged in the form of a full-line head having a width
corresponding to a width of a recording medium.
9. An ink jet head as claimed in claims 1 or 2, wherein each of said energy
generating elements is a heat generating resistor element.
10. An ink jet apparatus for performing a recording operation by ejecting
ink, comprising:
an ink jet head as claimed in claims 1 or 2, and
conveying means for conveying a recording medium past said ink jet head so
that said ink jet head can record on said recording medium.
11. An ink jet head including a plurality of ink liquid paths arranged in a
side-by-side relationship in a direction of arrangement, each of said ink
liquid paths having a height, each of said plurality of ink liquid paths
including an energy generating element for generating energy to eject an
ink, and a common liquid chamber having a pair of ends and ink supply
ports provided at both of the ends, and which is arranged substantially
parallel to the direction of arrangement of said plurality of ink liquid
paths for feeding ink to said plurality of ink liquid paths, so as to
eject the ink from a plurality of ink ejection outlets in fluid
communication with said ink liquid paths by driving the energy generating
elements, said ink jet head comprising;
an air chamber extending along an arrangement of said plurality of ink
liquid paths and communicated with said common liquid chamber by a
communication section located at a substantially bottom part of said
common liquid chamber, said air chamber having a height which is greater
than the heights of the ink liquid paths, said air chamber containing a
gas therein for absorbing a pressure fluctuation propagating in the ink
received in said common liquid chamber, and a part of said air chamber
that is located adjacent to said communication section being used as an
ink reserving portion.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an ink jet head for performing a
printing operation by ejecting ink to a recording medium, a method of
producing an ink jet head of the foregoing type, and an ink jet apparatus
operable using an ink jet head of the foregoing type. More particularly,
the present invention relates to improvement of an ink jet head, a method
of producing an ink jet head of the foregoing type and an ink jet
apparatus operable using an ink jet head of the foregoing type wherein the
ink jet head includes a chamber (serving as a buffer chamber) containing a
gas for suppressing ink vibration induced as the ink, i.e., a recording
liquid is ejected from a number of ink ejecting outlets.
2. Description of the Related Art
An ink jet system has been hitherto practiced such that a recording liquid
such as ink or the like (hereinafter referred to simply as ink) is ejected
from a plurality of fine liquid ejecting outlets (hereinafter referred to
as ink ejection outlets or simply as outlets) in the form of ink droplets
so that recording (which includes so-called printing) is achieved on a
recording material such as paper, plastic sheet, cloth or the like with
the liquid droplets shot thereon corresponding to recorded information or
figure information. The ink jet system offers advantages such that
recording can be achieved at a high speed and a plain paper or a similar
material can be used for a recording medium without any problem.
An ink jet apparatus used for practicing the ink jet system is equipped
with an ink jet head which includes a number of ink ejection outlets, an
ink path communicated with the respective ink ejection outlets, and a
plurality of energy generating elements in the liquid path such as
piezoelectric elements, heat generating resistors or the like for
generating the energy required for ink ejection in the liquid path. When a
recording operation is performed, ejection energy is first generated from
the energy generating elements, the generated heat is then applied to ink
in the liquid path to generate the pressure required for ink ejection, and
subsequently, ink is ejected from the ink ejection outlet so as to allow
ink droplets to be shot onto the recording material.
Solvent components such as water, aqueous organic solvent, non-aqueous
organic solvent or the like having a recording agent component such as
pigment, dye or the like dissolved or dispersed therein have been usually
used as ink to be used for ink jet recording.
The pressure required for ink ejection of the ink jet head is generated by
applying the thermal energy generated by the energy generating elements to
ink in the liquid path so that a part of the pressure is distributively
transmitted in the direction toward the ink ejection outlet via the ink in
the liquid path, while other part of the same is transmitted in the
direction toward a liquid chamber, i.e., in the opposite direction to the
ink ejection outlets. As the pressure transmitted to the ink ejection
outlets is applied to ink, the ink is squeezed out of the ink ejection
outlet so as to allow it to be ejected therefrom. When the ejected ink is
parted away from the ink ejection outlet in the form of ink droplets, the
meniscus formed in a liquid path in the vicinity of the ink ejection
outlet is retracted depending on a quantity of ejected ink, but after a
certain time elapses, the ink filled state having the liquid path filled
with ink is restored to the original state before ink ejection due to
surface tension which is effective for drawing the meniscus toward the ink
ejecting outlet. This phenomenon is called refill. When recording is
practically effected, the aforementioned actions are repeated, and stable
ink ejection can continuously be achieved as long as good refill occurs.
If ink ejection is continuously effected while refill occurs incorrectly,
this means that ink ejection is continuously effected while the meniscus
is incompletely returned to the proper ejection position after completion
of the ink ejection. As a result, a quantity of ejected ink is reduced.
For example, a diameter of each ink dot formed on a recording material by
ink droplets is reduced due to the shortage of the quantity of ejected
ink. Thus, recording can not be achieved with a predetermined quantity of
ink, resulting in the quality of the recorded image being extremely
degraded. In addition, such a phenomenon as mentioned above leads to the
result that a shooting accuracy of ejected ink droplets onto the recording
material is degraded, causing malfunctions such as vague appearance of a
recorded image, warpage of the recorded image, appearance of a stripe on
the recorded image and formation of white spots on the recorded image to
readily arise.
To solve the problems associated with the conventional liquid recording
technology like the aforementioned ink jet system, the structure of liquid
paths and associated components were improved and physical properties of
ink were correctively adjusted. In the case of an ink jet head including
number of ink ejection outlets, however, satisfactory improvable effects
could not often be obtained merely by the improvement and corrective
adjustment as mentioned above.
With a conventional ink jet head 100 including a number of ink ejection
outlets 101, a number of liquid paths 102, a number of energy generating
elements 103 and a common liquid chamber 104 as shown in FIG. 29A, when
ink is ejected from the ink ejecting outlets 101 at the same time or with
just a small time difference therebetween, the pressure is applied to ink
in each liquid path 102 in the direction toward the common liquid chamber
104 in such a manner as mentioned above, and the pressures arising in the
respective liquid paths 102 are integrated with each other in the common
liquid chamber 104 to generate a large magnitude of pressure therein. The
pressure arising in each liquid path 102 acts on ink as a squeezing power
so as to allow the ink to be squeezed in the direction toward the common
liquid chamber 104, i.e., in the direction of arrow A, and a total of the
pressures arising in the respective liquid paths 102 is enlarged several
times compared with an ink jet head including a single ink ejection
outlet. Thus, as shown in FIG. 29B, to assure that a good refill state is
maintained, it is necessary that a large quantity of ink is quickly
displaced in the direction toward the ink ejection outlets 101, i.e., in
the direction of arrow B, and moreover, to shift the displacement of ink
in the direction of arrow A to the displacement of ink in the direction of
arrow B, a high intensity of pressure enough to stand against the
aforementioned initial large inertia power (total pressure) is required.
However, the surface tension appearing on a meniscus 106 in the vicinity of
the ink ejection outlet 101 to serve as a motive power for inducing a
refill state in each liquid path 102 does not satisfactorily act so as to
instantaneously displace a large quantity of ink in the direction toward
the ink ejection outlets 101 against the aforementioned total pressure in
the direction toward the common liquid chamber 104. In other words, as the
initial inertia power induced by the displacement of ink is enlarged, a
longer time is required until each meniscus 106 is returned. When a
sufficiently long time is taken until each meniscus 106 is returned, there
arises a malfunction in that the recording speed is reduced. On the
contrary, in the case that a sufficiently long time can not be taken until
each meniscus 106 is returned, there arise malfunctions in that a
predetermined quantity of ink can not be ejected from each ink ejection
outlet 101 and acceptable recording can not be achieved.
A mechanism for appearance of the aforementioned phenomenon will briefly be
described below with reference to FIG. 30A which shows a curve of rearward
displacement of each meniscus.
A quantity of rearward displacement L (.mu.m) of a meniscus shown on an
ordinate in FIG. 30A represents a length L in a liquid path 102 on the ink
ejection outlet 101 side as shown in FIG. 30B. Specifically, the length L
is equal to a distance as measured from an ink ejection outlet 101 to the
rearmost end of an ink meniscus 106. In the case of an ink jet head
including a single ink ejection outlet, as shown by a curve C.sub.M1 in
FIG. 30A, at the time t.sub.0 ' that a certain time elapses from the time
t.sub.0 when the thermal energy generated by the energy generating element
103 is applied to ink in the liquid path 102, i.e., at the time when ink
ejection is effected, a meniscus 106 is positioned in the vicinity of the
ink ejection outlet 101, and it is then quickly displaced in the rearward
direction. Thereafter, a quantity of rearward displacement of the meniscus
106 is maximized at a time t.sub.1 ', and subsequently, the meniscus 106
starts to gradually return to the original position by the function of the
restoring power induced by the surface tension. Finally, refill is
completed at the time t.sub.1.
On the contrary, in the case of an ink jet head including number of ink
ejection outlets, as illustrated by a curve C.sub.M2, a quantity of
rearward displacement of the meniscus 106 is maximized at the same time as
the time t.sub.1 ' or at the time t.sub.2 ' slightly later than the time
t.sub.1 '. However, a maximum value of quantity of rearward displacement
of the meniscus 106 is small, and a refill speed of the meniscus 106 is
slow as represented by t.sub.2. It is considered that this is because a
total value of the pressures effective for squeezing ink from the liquid
paths 102 in the rearward direction largely exceeds the pressure effective
for flowing ink in the common liquid chamber 104, and the pressure which
has failed to flow ink is left as it is but the foregoing pressure serves
so as to allow a refill speed for returning the meniscus 106 to become
extremely slow.
The aforementioned phenomenon scarely appears after ink ejection is
continuously repeated, since ink steadily flows from an ink feed tube 105
(referring to FIGS. 29A and 29B) to the common liquid chamber 104.
However, it remarkably appears at the initial time of ink ejection,
especially until the ink flow becomes steady.
When the frequency of applying a recording signal to the energy generating
element 103 is set to be longer than the time between the time t.sub.0 and
the time t.sub.2 shown in FIG. 30A, no particular problems arise with the
reduction of the refill speed of the ink jet head including number of ink
ejection outlets 101. However, in the case that a recording signal is
applied to the energy generating unit 103 at the frequency shorter the
time between the time t.sub.0 and the time t.sub.2, when a next recording
signal is applied to the energy generating element 103 while refill is not
completed, e.g., a quantity of rearward displacement of the meniscus 106
is 30 .mu.m or more, a quantity of ejected ink droplets is reduced,
preventing good recording from being achieved.
To solve the foregoing problem, a structure including atmosphere opening
portions each located in the vicinity of a liquid path communicated with a
common liquid chamber so as to absorb in the foregoing opening portion the
pressure effective in the direction toward the common liquid chamber at
the time of ink ejection is disclosed in an official gazette of U.S. Pat.
No. 4,578,687. With this structure disclosed in the prior art, however,
since the common liquid chamber is exposed to an atmosphere, a solvent
containing contained in the ink is vaporized to the outside via the
atmosphere opening portions. Thus, there arise problems that a viscosity
of ink in the ink jet head is increased, and moreover, the liquid path and
the ink ejecting outlets are clogged with precipitated solid substances
contained in ink, causing incorrect printing to be readily effected. In
addition, another problem is that a gas bubble grows in the common liquid
chamber due to the influence of vibration or the like, resulting in
special designing becoming necessary for the purpose of preventing a
foreign matter such as dust or the like from entering the ink jet head.
For this reason, the above-proposed structure does not exhibit any
sufficient practicability.
In view of the foregoing problems, an assignee common to the present
invention proposed a ink jet head including a pressure-volume converting
unit capable of reversibly converting the pressure associated with refill
into variation of a volume as disclosed in an official gazette of Japanese
Patent Application Laying-Open No. 308644/1989. Specifically, according to
the prior art, the ink jet head includes means for keeping gas bubbles in
a liquid chamber.
In practice, the ink jet head proposed by the assignee contributes to the
elimination of the aforementioned problems. However, to assure that the
ink jet head is constructed in such a manner as to include a
pressure-volume converting unit in the liquid chamber or adjacent to the
liquid chamber, new components and a new process are additionally
required. This leads to the result that the ink jet head is produced at
the correspondingly increased cost.
With the ink jet head constructed as disclosed according to the prior art,
as shown in FIG. 31, buffer chambers 7, 7 having gas bubbles 72, 72 grown
therein are disposed sidewards of the array of energy generating elements.
In the case of an ink jet head as described above, when it includes a
small number of energy generating elements, liquid vibration can be
absorbed satisfactorily in the buffer chamber 7. However, when the ink jet
head includes a large number of energy generating elements, e.g., several
thousand energy generating elements, the liquid vibration can not always
be absorbed satisfactorily in the buffer chamber 7. When the buffer
chamber 7 contains large size of gas bubble so as to assure a sufficient
buffer effect, it is unavoidably designed with large dimensions. Thus, in
the case that the buffer chambers 7, 7 are disposed sidewards of the array
of the energy generating elements, the ink jet head is undesirably
enlarged.
To produce an ink jet head of the foregoing type, there has been known a
method wherein a plate of glass or metallic material is used as a material
for a base board, a groove is formed on the plate by employing a cutting
process, an etching process or the like, and thereafter, another base
board having a piezoelectric element for generating energy for the purpose
of ink ejection and a driving element such as an electrothermal converting
element or the like attached thereto is connected to the first-mentioned
base board so as to form a fine ink ejecting outlet, an ink flow path or
the like.
However, when the foregoing method is practically employed for producing an
ink jet head, it is difficult to prepare an air chamber large enough to
correspond to an ink jet apparatus. In addition, it is difficult to
produce easily the whole ink jet apparatus at a high yielding rate while
maintaining a high dimensional accuracy. Especially, with the ink jet
apparatus produced by employing the aforementioned conventional method,
ink ejecting characteristics readily fluctuate due to coarse surface
roughness on a flow path. In addition, when the cutting process is
employed, breakage or cracking readily occurs on the material to be
worked. Consequently, the ink jet apparatus is produced at a low yielding
rate. On the other hand, when the etching process is employed, the ink jet
head is produced at an increased cost due to many production steps
required for production thereof. Another problem is that when two base
boards, i.e., a first base board and a second base board are connected to
each other, it is difficult to have the first base board correctly aligned
with the second base board, and so the ink jet head is mass produced only
with much difficulty. To eliminate the aforementioned problems inherent to
the conventional method, the assignee invented a method of producing a
liquid jet head wherein an active energy ray setting material is used as a
material for forming a liquid path therein, and filed an application for
patent under Japanese Patent Application Laying-Open No. 154947/1986.
However, it has been found that this method is not always satisfactory in
respect of a size and a height to be determined for each of a common
liquid chamber communicated with an ink liquid path, an air chamber and
associated components. Especially in the case of the so-called full line
liquid jet apparatus including number of ink ejection outlets arranged at
a high density across the whole width of a recording material such as a
paper or the like so as to simultaneously eject ink from the ink ejection
outlets, there arises a significant problem in that it is difficult from
the viewpoint of economical production of the liquid jet apparatus to
additionally form an air chamber in a liquid jet head.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an ink jet head and an ink
jet apparatus which assure that a capability of ink refilling can
substantially be improved without any occurrence of a malfunction where
ink is incorrectly ejected especially at the beginning time of a recording
operation, and moreover, they can be produced at an inexpensive cost with
high speed responsiveness and excellent ink ejection stability.
Another object of the present invention is to provide a method of producing
an ink jet head at an inexpensive cost on the basis of mass production
wherein there rarely arise a malfunction where ink is incorrectly ejected
from the ink jet head after the ink ejection outlets are not used for a
long time, and moreover, high speed recording can be achieved at a high
driving frequency.
In the first aspect of the present invention, an ink jet head includes a
plurality of ink liquid paths arranged in the side-by-side relationship,
each of the ink liquid paths including an energy generating element for
generating energy required for ink ejection, and a common liquid chamber
arranged in substantially parallel with a direction of arrangement of the
plurality of ink liquid paths for feeding ink to the ink liquid paths, so
as to eject ink from a plurality of ink ejection outlets by driving the
energy generating elements, the ink jet head comprises;
an air chamber extending along an arrangement of the plurality of ink
liquid paths and communicated with the common liquid chamber via a
communication section located at the substantially central part thereof,
the air chamber containing gas therein for absorbing pressure fluctuation
propagating in the ink received in the common liquid chamber.
Here, the air chamber may be divided into plural segments.
The communication section may include a plurality of communication path
walls.
A volume of the common liquid chamber may be larger than that of the air
chamber.
A cross-sectional area of each of the ink liquid paths may be equal to or
larger than that of each of a plurality of communication paths defining
the communication section.
A total of the sectional areas of the communication paths defining the
communication section may be equal to twice or more of value obtained by
converting a total quantity of ink simultaneously ejected from all the ink
ejection outlets into an area.
A total of the sectional areas of the communication paths defining the
communication section may be equal to 1/10 or more of the total
cross-sectional area of the ink flow paths.
The ink ejection outlets may be arranged in the form of a full-line head
having a width corresponding to a width of a recording medium.
Each of the energy generating elements may be a heat generating resistor
element.
In the second aspect of the present invention, an ink jet apparatus for
performing a recording operation by ejecting ink includes:
an ink jet head including a plurality of ink liquid paths arranged in the
side-by-side relationship, each of the ink liquid paths including an
energy generating element for generating energy required for ink ejection,
and a common liquid chamber arranged in substantially parallel with a
direction of arrangement of the plurality of ink liquid paths for feeding
ink to the ink liquid paths, so as to eject ink from a plurality of ink
ejection outlets by driving the energy generating elements. The ink jet
head also includes:
an air chamber extending along an arrangement of the plurality of ink
liquid paths and communicated with the common liquid chamber via a
communication section located at the substantially central part thereof,
the air chamber containing gas therein for absorbing pressure fluctuation
propagating in the ink received in the common liquid chamber, or the ink
jet head where the air chamber is divided into plural segments, and
conveying means for conveying a recording medium.
In the third aspect of the present invention, a method of producing an ink
jet head including a plurality of ink ejecting outlets for ejection ink
therefrom, a plurality of ink liquid paths communicated with the ink
ejection outlets, a plurality of energy generating elements arranged
corresponding to the ink liquid paths, a common liquid chamber for feeding
ink to the ink liquid paths, and an air chamber communicated with the
common liquid chamber via a communication section, via the steps of;
providing a first base board having the plurality of energy generating
elements arranged thereon in the side-by-side relationship,
forming on the first base board, a mold member for forming the plurality of
ink liquid paths, the common liquid chamber for feeding ink to the ink
liquid paths, and the communication section;
disposing a filling member in such a manner as to cover the mold member
therewith,
disposing a second base board having a groove formed thereon to constitute
the common liquid chamber and the air chamber, and removing the mold
member.
Here, the filling member may be a photosensitive resin, further comprising
the step of conducting exposure treatment for removing a part of the
filling member corresponding to the groove on the second base board, and
moreover, removing a part of the mold member corresponding to the groove
after the step of disposing the second base board.
A plurality of the communication sections may be formed using the mold
member, and a plurality of the air chambers are formed by sealably closing
each air chamber between adjacent communication sections.
The above and other objects, effects, features and advantages of the
present invention will become more apparent from the following description
of the embodiment thereof taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view which shows the fundamental structure of an
ink jet head constructed according to the present invention;
FIG. 2 is a fragmentary sectional plan view of the ink jet head of the
present invention taken along a line 2/5A/7--2/5A/7 in FIG. 1;
FIG. 3 is an enlarged vertical sectional view of the ink jet head of the
present invention taken along a line 3/5B/8--3/5B/8 in FIG. 1;
FIGS. 4A and 4B are fragmentary sectional plan views of the ink jet head of
the present invention, particularly showing a behavior of ink at the time
of ink ejection;
FIGS. 5A and 5B are fragmentary sectional plan views of an ink jet head
constructed according an embodiment of the present invention, particularly
showing the structure of the ink jet head taken along a line
2/5A/7--2/5A/7 and a line 3/5B/8--3/5B/8 in FIG. 1, respectively;
FIGS. 6A and 6B are fragmentary sectional plan views of the ink jet head
shown in FIGS. 5A and 5B, particularly showing a behavior of ink at the
time of ink ejection;
FIG. 7 is a fragmentary sectional plan view of an ink jet head constructed
according to other embodiment of the present invention, particularly
showing the structure of the ink jet head taken along a line
2/5A/7--2/5A/7 in FIG. 1;
FIG. 8 is an enlarged vertical sectional view of the ink jet head shown in
FIG. 7, particularly showing the structure of the ink jet head taken along
a line 3/5B/8--3/5B/8 in FIG. 1;
FIGS. 9A, 9B and 9C are fragmentary sectional plan views of an ink jet head
constructed according to a modified embodiment of the present invention,
respectively;
FIG. 10A is a fragmentary sectional plan view of an ink jet head,
particularly showing the state that a mold member is placed on a first
base board by employing a method of producing the ink jet head according
to the present invention;
FIG. 10B is a fragmentary sectional plan view of the ink jet head,
particularly showing the state that a second base board is placed on the
first base board with a filling member interposed therebetween by
employing the method of the present invention;
FIGS. 11A and 11B are enlarged fragmentary vertical sectional view of the
ink jet head taken along a line 11A--11A and a line 11B--11B in FIG. 10A,
respectively;
FIGS. 12A and 12B are enlarged fragmentary vertical sectional views of the
ink jet head taken along a line 12A--12A and a line 12B--12B in FIG. 10B,
particularly showing a step of irradiating active energy rays,
respectively;
FIG. 13A is an enlarged fragmentary vertical sectional view of the ink jet
head shown in FIG. 12A, particularly showing the state that the mold
member is removed therefrom;
FIG. 13B is an enlarged fragmentary vertical sectional view of the ink jet
head shown in FIG. 12B, particularly showing the state that the filling
member is removed therefrom;
FIG. 14 is a perspective view of the ink jet head, particularly showing the
intermediate state that a mold member layer is placed on the first base
board by employing the method of the present invention;
FIG. 15 is a perspective view of the ink jet head, particularly showing the
intermediate state that a solid mold member layer is laminated on the mold
member layer shown in FIG. 14 by employing the method of the present
invention;
FIG. 16 is a perspective view of the ink jet head, particularly showing the
intermediate state that a second base board is laminated on the solid mold
member layer shown in FIG. 15 by employing the method of the present
invention;
FIG. 17 is a perspective view of the ink jet head, particularly showing the
intermediate state that a photo-mask is placed on a part of the second
base board shown in FIG. 16 and active energy rays are irradiated then
toward the second base board;
FIG. 18 is a perspective view of the ink jet head, particularly showing the
intermediate state that an unhardened part and the mold member layer are
dissolutely removed after the step shown in FIG. 17;
FIG. 19 is a sectional view of the ink jet head, particularly showing that
a malfunction arises when ink is filled in a single air chamber through a
plurality of communication paths;
FIG. 20 is a perspective view of the ink jet head constructed according to
another embodiment of the present invention, particularly showing the
first base board and the second base board in the disassembled state;
FIG. 21A is a fragmentary plan view of the ink jet head, particularly
showing by way of example that plural air chambers are formed by using
plural partition members;
FIG. 21B is a vertical sectional view of the ink jet head taken along a
line 21B--21B in FIG. 21A;
FIG. 22A is a fragmentary plan view of the ink jet head, particularly
showing by way of other example that plural air chambers are formed by
using plural partition members;
FIG. 22B is a vertical sectional view of the ink jet head taken along a
line 22B--22B in FIG. 22A;
FIG. 23 is a fragmentary plan view of the ink jet head, particularly
showing by way of another example that plural air chambers are formed by
using plural partition members;
FIGS. 24A and 24B are perspective views of the ink jet head, particularly
showing an intermediate step of the method of the present invention;
FIG. 25 is a perspective view of the ink jet head, particularly showing by
way of example the structure of the ink jet head;
FIG. 26 is a perspective view of the ink jet head, particularly showing by
way of another example the structure of the ink jet head;
FIG. 27 is a schematic perspective view of an ink jet apparatus constructed
according to the present invention, particularly showing by way of example
the structure of the ink jet apparatus;
FIG. 28 is a perspective view of the ink jet apparatus, particularly
showing by way of another example the structure of the ink jet apparatus;
FIGS. 29A and 29B are fragmentary sectional plan views of a conventional
ink jet head, particularly showing a behavior of ink at the time of ink
ejection;
FIG. 30A is a diagram which shows characteristic curves at the time of ink
refilling;
FIG. 30B is an enlarged fragmentary sectional plan view of the conventional
ink jet head, particularly showing the structure of an ink refilling
mechanism; and
FIGS. 31A and 31B are schematic fragmentary sectional plan views of the
conventional ink jet head, particularly showing a behavior of gas bubbles,
respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be described in detail hereinafter with
reference to the accompanying drawings which illustrate preferred
embodiments thereof.
FIG. 1 is a perspective view of an ink jet recording head constructed
according to a first embodiment of the present invention, FIG. 2 is a
sectional view of the recording head shown in FIG. 1, and FIG. 3 is an
enlarged vertical sectional view of the recording head taken along a line
3/5B/8--3/5B/8 in FIG. 1. In these drawings, reference numeral 1
designates a first base board (heater board) made of a silicon substrate
and having a plurality of energy generators (not shown), e.g.,
electrothermal converting elements (hereinafter referred to as ejection
heaters) and number of wiring conductors each made of aluminum or the like
for feeding electricity to the ejection heaters formed thereon by
employing a film forming technique, reference numeral 2 designates an
ejection portion forming member (solid layer) having number of ink
ejection outlets 101 for ejecting ink therefrom and number of liquid paths
102 communicated with the ejection outlets 101 formed therein,
respectively, and reference numeral 3 designates a second base board for
structuring a common liquid chamber 104 being communicated with the liquid
paths 102 formed therein and having ink to be fed to the liquid paths 102
stored therein. The solid layer for constructing the liquid paths 102 and
being formed corresponding to the ejection heaters is laminated on the
first base board 1, and a second base board 3 is laminated on the solid
layer. The first base board 1 is positionally fixed on a base plate 4, and
a flexible base board 5 for feeding electrical signals therethrough for
the purpose of ejecting ink is exactly located relative to an electrical
pad placed on the first base board 1. In addition, the base board 5 is
firmly fixed to the base plate 4 in the compressed state by securing a
flexible retainer 6 by tightening a bolt (not shown).
In this embodiment, as shown in FIG. 2 and FIG. 3, a recording head 10
includes an air chamber (serving as a buffer chamber) in the second base
board 3 located outside of a liquid chamber 104, and the liquid chamber
104 and the air chamber 7 are preformed in the form of two longitudinally
extending parallel grooves by employing a cutting process or an
injection-molding process before the second base board 3 is laminated on
the solid layer 2.
When the liquid paths 102 are formed across the solid layer 2, a
communication portion 8 is formed between the liquid chamber 104 and the
air chamber 7 at substantially the center of the liquid paths 102 as seen
in the longitudinal direction so as to establish communication
therebetween. Ink feed tubes 11A and 11B (referring to FIG. 1) are
connected to the opposite ends of the liquid chamber 104 via ink feed
joints 9A and 9B, while the rear ends of the ink feed tubes 11A and 11B
are connected to an ink tank (not shown). Incidentally, the opposite ends
of the air chamber 7 are sealably closed with an adhesive or a similar
material.
Next, a behavior of ink during a recording operation to be performed by ink
ejection will be described below with reference to FIGS. 4A and 4B.
With the ink jet head 10 constructed in the above-described manner, first,
ink is fed to the ink liquid chamber 104 from the ink tank via the ink
feed tubes 11A and 11B. While the liquid chamber 104 and the liquid paths
102 are filled with ink, in response to a recording electrical signal fed
to the ejection heaters 103, thermal energy is generated by the ejection
heaters 103, causing the ink in the liquid paths 102 to be heated, whereby
ink droplets are ejected from number of ejection outlets 101 in conformity
with the aforementioned pressure transmission mechanism to achieve a
recording operation.
As shown in FIG. 4A, a low intensity of squeezing power for squeezing ink
toward the ink liquid path 104 from the respective liquid paths 102 in the
direction of arrow A appears every time ink ejection is completed.
However, since the ink liquid chamber 104 is communicated with the air
chamber 7, the foregoing pressure derived from the respective liquid paths
102 is absorbed in two regions 7A and 7B of the air chamber 7.
Consequently, the generation of the power effective for returning ink from
the ink liquid chamber 104 to the ink feed tubes 11A and 11B in the
direction of arrow C is suppressed or prevented. Subsequently, as shown in
FIG. 4B, in the circumstances as mentioned above, the surface tension of
ink appearing over each meniscus 106 formed by ink ejection is transformed
into the power for displacing ink in the direction of extension of each
liquid path 102, resulting in ink refilling being started. At this time,
the restoring power of the air in both the regions 7A and 7B of the air
chamber 7 is applied to the liquid chamber 104 so that it functions in the
direction of arrow B so as to compensate the power for displacing ink in
the direction toward ink ejection outlets during the ink refilling
operation.
In the case that the ink jet head 10 does not include any air chamber such
as the air chamber 7 or the like, the power effective for squeezing ink
from the liquid paths 102 in the direction toward the liquid chamber 104
acts on the refilling power in the opposite direction. In contrast with
the foregoing case, in this embodiment, the power effective for squeezing
ink from the liquid paths 102 in the direction toward the liquid chamber
104 is absorbed in both the regions 7A and 7B of the air chamber 7. In
other words, this power effectively functions in such a manner as to
compensate for the power for achieving ink refilling. Accordingly, ink
refilling can smoothly be achieved for a short time. This makes it
possible that the ink jet head 10 can respond to the high driving
frequency, and moreover, an excellent quality image can be recorded at a
high speed.
In addition, in this embodiment, since the air chamber 7 is arranged
substantially in parallel with the liquid chamber 104 common to a row of
the energy generating elements and with the direction of the array of the
ink liquid paths, gas sufficient to assure a buffer effect can be reserved
in the ink jet head 10 without any necessity for enlarging the ink jet
head 10 itself. Furthermore, this arrangement enables the air chamber to
be long and slender so that the power of air in the air chamber is very
effective to compensate for the power for achieving ink refilling.
The communication portion 8 can formed at the same time when number of
liquid paths 102 are formed through the solid layer 2. A method of forming
the communication portion 8 and the liquid paths 102 will be described in
detail later. Here, it is assumed that a communication portion to be
described hereinafter represents the whole communication forming region
inclusive of a plurality of walls defined between adjacent communication
paths (hereinafter referred to as communication path forming walls) in the
case that a plurality of communication paths are concentratively formed in
a single region.
Next, an ink jet head constructed according to a second embodiment of the
present invention will be described below with reference to FIG. 5. In
contrast to the first embodiment of the present invention, in this
embodiment, the length of an air chamber as seen in the longitudinal
direction of the head is substantially equally divided into plural air
chamber segments, i.e., air chamber segments 71, 72 and 73. Reference
numerals 12A and 12B designate partition walls for the air chamber
segments 71, 72 and 73. With this construction, the three air chambers 71,
72 and 73 are communicated with common ink chamber 104 via three
communication paths 8A, 8B and 8C each located at the central part of each
air chamber segment. Since the ink liquid chamber 104 is constructed in
the above-described manner, the ink pressure transmitted from the liquid
chamber 104 via the communication paths 8A, 8B and 8C during ink ejection
can be absorbed in a plurality of air regions 71A, 71B, 72A, 72B, 73A and
73B (see FIG. 6) located in the vicinity of the communication paths 8A, 8B
and 8C. Specifically, the ink pressure transmitted in that way is
conducted and then absorbed in a first air region section including the
air regions 71A and 71B located on the opposite sides relative to the
communication path 8A, a second air region section including the air
regions 72A and 72B located on the opposite sides relative to the
communication path 8B and a third air region including the air region 73A
and 73B located on the opposite sides relative to the communication path
8C.
Next, a manner of absorbing the ink pressure will be described below with
reference to FIGS. 6A and 6B. Since the behavior of ink in the liquid
chamber 104 during ink ejection has been described above in the first
embodiment of the present invention, repeated description is omitted. In
this embodiment, on completion of ink ejecting, the power effective for
squeezing ink away from the respective liquid paths 102 in the direction
of arrow A is applied to the liquid chamber 104 as shown in FIG. 6A. In
this embodiment, the foregoing power is dispersively or distributively
transmitted to air chambers 71, 72 and to 73 depending on the state of ink
injection, and thereafter, absorbed in the air regions 71A and 71B of the
air chamber 71, the air region 72A and 72C of the air chamber 72, and the
air regions 73A and 73B of the air chamber 73. At the time of subsequent
ink ejection, as shown in FIG. 6B, the power absorptively reserved in the
air chambers 71, 72 and 73 is transmitted to the liquid chamber 104, and
thereafter, it is applied to the respective liquid paths 102 in the
direction of arrow B. Since the thus applied power cooperates with the
surface tension appearing on each meniscus 106 so as to allow the
resultant power to function as a power for returning ink to the respective
liquid paths 102, a sufficient quantity of ink for achieving subsequent
ink ejection can be supplemented to the respective liquid paths 102.
As described above, in this embodiment, a plurality of communication paths
are formed between the central part of the air chamber and the common
liquid chamber both of which extend in parallel to each other in the
longitudinal direction of the second base board 3, so that plural sets of
air regions are formed on the opposite sides of each communication path,
and moreover, the communication paths are located at the positions remote
from the ink supply routes. Thus, a behavior of ink at the time of ink
ejecting can effectively be controlled, and an ink refilling operation can
smoothly be achieved for the respective ink paths. The structure of the
ink jet head employed according to the second embodiment of the present
invention is preferably employable especially in the case that a number of
ink ejection outlets and ink liquid paths are formed in the longitudinal
direction.
Next, the structure of an ink jet head preferably employable for
effectively absorbing ink vibration and pressure waves induced at the time
of ink ejecting will be described below. Here, the ink jet head is
exemplified by the structure as shown in FIG. 7. Alternatively, the
structure of the ink jet head shown in FIG. 5 may be employed.
FIG. 7 is a fragmentary sectional plan view of an ink jet head constructed
according to a modified embodiment of the present invention, particularly
showing that a single air chamber 7 is arranged in parallel with a common
liquid chamber 104. In this drawing, reference numeral 8 designates a
communication portion which is disposed at the substantially central part
of the ejection head 20 as seen in the longitudinal direction. In this
embodiment, the communication portion 8 includes a plurality of
communication paths 8A arranged in the longitudinal direction. Reference
numeral 8B' designates a communication path forming wall which has two
communication paths 8A, 8A located adjacent thereto. Also, in this
embodiment, the common communication chamber 104 is designed to have a
sufficiently large capacity compared with the air chamber 7. In the case
that the ink jet head 20 includes a plurality of communication paths 8A
for a single air chamber 7, to assure that the pressure generated toward
the common liquid chamber 104 side at the time of ink ejecting through a
number of ink paths 102 is quickly absorptively received, it is
recommended that the number of communication paths or the total sectional
area of the latter is increased.
In view of the foregoing fact, a series of development works were conducted
for increasing the number of communication paths 8A. It was found based on
the results obtained from the development works that a width of each
communication path forming wall 8B' became excessively narrow, and
moreover, a first base board 1 was readily be peeled away from a second
base board 3 at a part of the communication path forming wall 8B'
constituting the solid layer 2 due to shortage of the strength.
To eliminate the foregoing problems, a series of experiments as noted below
were conducted to determine optimum conditions for the communication paths
8A and the communication path forming walls 8B' in the communication
portion 8. For the purpose of convenience, a preset height of each ink
ejection liquid path 102 is designated by h1, a preset width of the same
is designates by a, a preset height of each communication path 8A is
designated by h2 and a preset width of the same is designated by b, and a
preset width of each communication path forming wall 8B' is designated by
c. Specifically, in this embodiment, the sectional area of ink liquid path
is represented by a h1 and the sectional area of the communication path is
represented by b h2. Table 1 shows main comparison items of recording
heads A, B and C used for the experiments.
TABLE 1
__________________________________________________________________________
width of
height of width of
number of
liquid
liquid
pitch of
number of
width of
height of
communication
name of
liquid
path
path liquid
communication
communication
communication
path forming
head
paths
(.mu.m)
(.mu.m)
path
paths (.mu.m)
path (.mu.m)
path (.mu.m)
wall (.mu.m)
__________________________________________________________________________
A 4736 38 24 400 dpi
20 1000 24 1000
B 2048 65 48 203 dpi
16 1000 48 1000
(8 pel)
C 1472 42 24 360 dpi
14 500 24 500
__________________________________________________________________________
A function and a mechanical strength of the communication portion 8 were
examined with respect to all the experiment recording heads, and after
completion of the examination, it was confirmed that both the items were
satisfactorily acceptable. In association with structural conditions for
the communication portion 8, the following two inequalities are
established.
1. a.multidot.h1.ltoreq.b.multidot.h2
2. b.ltoreq.c
With the recording head 20 constructed in the above-described manner, ink
vibration and pressure waves can be absorbed more effectively, and
moreover, each liquid path 102 can be refilled smoothly with ink in a
short time. This makes it possible to increase a response frequency and
largely contributes to practical realization of high speed recording.
Next, an ink jet head constructed according to the third embodiment of the
present invention will be described below with reference to FIG. 8. The
recording head 30 includes a communication portion 8 of which
communication path 8A is dimensioned to have a height h2 higher than a
height h1 of each liquid path 102. In this case, the recording head 30 can
easily be fabricated by equalizing the height h2 of the communication path
8A to a height of the solid layer 2, i.e., a thickness of the same when
the solid layer 2 is formed as will be described later. In this
embodiment, if the width b of the communication path 8A is set to be equal
to the width a of the liquid path 102, an effective refilling effect can
be expected by satisfying the condition that a sectional area, that is, b
h2 of the communication path 8A is set to be larger than a sectional area
a h1 as represented in the above inequality 1.
Next, an ink jet head constructed according a modified embodiment of the
present invention modified from the second embodiment of the same will be
described below with reference to FIG. 9A to FIG. 9C wherein the
arrangement or shape of each communication path 8A is designed to be
suitable for an ink refilling operation. Specifically, in the modified
embodiment shown in FIG. 9A, a plurality of communication paths 8A formed
at the substantially central part of a common liquid chamber 104 and an
air chamber 7 are not arranged with an equally spaced relationship but as
shown in the drawing, a width of each communication path forming wall 8B'
is widened from the central part toward the opposite sides. Reference
characters C1 to C3 designate a width of each communication path forming
wall 8B' and reference character b designates a width of the communication
path 8A. As is apparent from the drawing, the width C3 of the outer
communication path forming wall 8B' is dimensioned to be larger than the
width C2 of the intermediate communication path forming wall 8B', and the
width C2 of the intermediate communication path forming wall 8B' is
dimensioned to be larger than the width C1 of the central communication
path forming wall 8B'. With this construction, the pressure generated in
the liquid paths 102 located remote away from the central part of the
recording head 20 is conducted to the air chamber 7 via the communication
path 8A located in the vicinity of the foregoing liquid paths 102 so as to
enable the original ink paths 102 to be refilled with ink.
FIG. 9A and FIG. 9B illustrate the case that a sectional shape of each
communication path forming wall 8B' is modified in such a manner that the
opposite end surfaces of each communication path forming wall 8B' are
configured to exhibit a U-shaped contour (FIG. 9B) or a V-shaped contour
(FIG. 9C) in the symmetrical relationship relative to the central
communication path 8A. With this construction, the pressure generated in
the respective liquid paths 102 is easily conducted to the opposite air
regions 71A and 71B of the air chamber 7 via the U-shaped or V-shaped
communication paths 8A, and thereafter, it is possibly uniformly returned
to the liquid chamber 104 side. An advantage obtainable form the modified
embodiment is that the strength of the communication portion 8 and
associated portions can be increased by contouring the respective
communication path forming wall 8B' in that way.
Next, a more acceptable contour of the communication portion in the
modified embodiment will be described below.
For example, with the structure of the recording head 20 as shown in FIG. 7
and FIG. 8, on the assumption that the number of liquid paths 102 is
designated by n, a width of the same is represented by a, that a height of
the same is represented by h1, and that the number of communication paths
8A is designated by m, a width of each communication path 8A is
represented by b and a height of the same is represented by h2, the liquid
paths 102 and the communication paths 8A are constructed in such a manner
as to establish the following inequality under a condition that the
conditions shown in the second embodiment are satisfied.
m.multidot.b.multidot.h2.gtoreq.1/10.multidot.n.multidot.a.multidot.h1(3)
Incidentally, the reason why the inequality (3) is established will be
described on the basis of the results obtained from the experiments
conducted by the inventors as will be described later.
TABLE 2
__________________________________________________________________________
width of
height of
name of
number
width of
height of
pitch number of
communi-
communi-
pitch of
experi-
of liquid
liquid
of communi-
cation
cation
communi- quality
mental
liquid
path
path liquid
n.a.h1
cation
paths
paths
cation of
head
paths n
a (.mu.m)
h1 (.mu.m)
path
(.mu.m)
paths m
b (.mu.m)
h2 (.mu.m)
paths (.mu.m)
m.b.h2 (.mu.m)
printing
__________________________________________________________________________
A1 4736
38 24 400 dpi
4.32 .times. 10.sup.6
64 40 24 400 dpi
6.14 .times. 10.sup.4
X
A2 4736
38 24 400 dpi
4.32 .times. 10.sup.6
10 1000 24 2000 2.4 .times. 10.sup.5
X
A3 4736
38 24 400 dpi
4.32 .times. 10.sup.6
15 1000 24 2000 3.6 .times. 10.sup.5
.DELTA.
A4 4736
38 24 400 dpi
4.32 .times. 10.sup.6
20 1000 24 2000 4.8 .times. 10.sup.6
.oval-hollow.
__________________________________________________________________________
Specifically, the inventors conducted a series of experiments at a driving
frequency higher than that during an ordinary recording operation using
experimental articles A1 to A4 of recording heads of which the number of
communication paths is represented by m, the width of which is represented
by b and the height of which is represented by h2 as shown in Table 2. It
was found from the results obtained from the evaluation on a quality of
each recording operation that the experimental articles of recording heads
A1 and A2 exhibited slight fluctuation in a quality of recording, the
experimental articles of recording head A3 exhibits an excellent quality
of recording, and the experimental article of recording head A4 exhibits a
more excellent quality of recording operation. Subsequently, the inventors
prepared experimental articles of recording heads A4, B and C as shown in
Table 3 with reference to the results obtained from the results on a
quality of each preceding recording operation and then conducted
experiments again using the experimental articles of recording heads A4, B
and C. On completion of the experimental recording operations, it was
found that each of the experimental articles of recording heads A4, B and
C exhibited an acceptable quality of recording operations.
TABLE 3
__________________________________________________________________________
width of
height of
pitch of
name of
number
width of
height of number of
communi-
communi-
communi-
experi-
of liquid
liquid
pitch of communi-
cation
cation
cation
mental
liquid
path
path liquid
1/10 (n.a.h1)
cation
paths
paths
paths
m.b.h2
head
paths n
a (.mu.m)
h1 (.mu.m)
path (.mu.m)
paths m
b (.mu.m)
h2 (.mu.m)
(.mu.m)
(.mu.m)
__________________________________________________________________________
A4 4736
38 24 400 dpi
4.32 .times. 10.sup.5
20 1000 24 2000 4.80 .times. 10.sup.5
B 2048
65 48 203 dpi
6.39 .times. 10.sup.5
16 1000 48 2000 7.68 .times. 10.sup.5
(8 pel)
C 1472
42 24 360 dpi
1.48 .times. 10.sup.5
14 500 24 1000 1.68 .times. 10.sup.5
__________________________________________________________________________
Next, a recording head constructed according to another embodiment of the
present invention will be described below. This embodiment is likewise
concerned with a total sectional area of communication paths forming a
communication portion and a total sectional area of liquid paths. In this
embodiment, a quantity of ink ejected every ejection is substituted for
the number of communication paths and a sectional area of the latter are
set in association with the quantity of ejected ink.
To look for set conditions, a quantity of ejected ink was detected using
experimental articles of recording heads A4, B and C each constructed in
the same manner as shown in Table 3. The results obtained from the
detection are shown in Table 4.
TABLE 4
__________________________________________________________________________
width of
height of
pitch of
number
width of
height of
volume number of
communi-
communi-
communi-
of liquid
liquid
pitch of
of ink communi-
cation
cation
cation
name of
liquid
path
path liquid
droplet cation
path paths
paths
m.b.h2
head
paths n
(.mu.m)
(.mu.m)
path
V (pl)
k.v.n
paths m
b (.mu.m)
h2 (.mu.m)
(.mu.m)
(.mu.m.sup.2)
__________________________________________________________________________
A4 4736
38 24 400 dpi
30 2.84 .times. 10.sup.5
20 1000 24 2000 4.80 .times. 10.sup.5
B 2048
65 48 203 dpi
180 7.37 .times. 10.sup.5
16 1000 48 2000 7.68 .times. 10.sup.5
(8 pel)
C 1472
42 24 360 dpi
40 1.18 .times. 10.sup.5
14 500 24 1000 1.68 .times. 10.sup.5
__________________________________________________________________________
K: 2(.mu.m.sup.2 /pl)
The results obtained from evaluation on a quantity of recording using the
experimental articles of recording heads A4, B and C as shown in Table 4
are same as those described with reference to Table 3. Thus, the
relationship represented by the following inequality (4) was obtained
based on a quantity of ejected ink (pl; coefficient of converting volume
into area) as shown in Table 4.
m.multidot.b.multidot.h2>k.multidot.V.multidot.n (4
where k is a coefficient used for converting ink ejection volume into area
and, in this embodiment determined to be the value of 2(.mu.m.sup.2 /pl)
on the basis of the result of several kinds of experiments, and V is
quantity of ink ejected from a single ejection outlet every single
ejection.
According to a fifth embodiment of the present invention, the number of
communication paths 8A, a width of the same and a height of the same are
set in such a manner as to settle the inequality (4).
Next, a method of producing an ink jet head according to the present
invention will be described in below.
FIG. 10 shows by way of fragmentary sectional view that number of ink
liquid paths 102 and a mold member 20 for forming a communication portion
8 are disposed on a first base board 1 including number of energy
generating portions 103 (e.g., heat generating resistance elements or
ejection heaters each serving to feed thermal energy to ink in the shown
case) and circuits (not shown) for driving the ink ejecting energy
generating portions 103. In this embodiment, the mold member 20 is
represented by a plurality of hatched lines in the drawing and contoured
in the form of a convex portion. The white part of the first base board 1
in the drawing is an upper surface of the same, and a plurality of a
concave portion 21 each serving as a column portion 8B of the
communication port 8 are formed on the white part of the first base board
1 at a subsequent step. Thus, the first base board 1 is visually
recognized below the mold member 20. In this embodiment, the mold member
20 is formed in the location other than that corresponding to the ink
liquid paths and the communication portions but the formation of the
foregoing location is not always required. In practice, the mold member 20
is removed from the first base board 1 at a subsequent step.
A material and means employed for the forming the mold member 20 will
concretely be described below.
(1) The mold member 20 is formed using a photosensitive dry film in
accordance with a so-called dry film image forming process.
(2) A solvent soluble polymer layer having a predetermined thickness and a
photoresist layer are laminated on the first base board 1 one above
another, and after a pattern is formed on the photoresist layer, the
solvent soluble polymer layer is selectively removed from the first base
board 1.
(3) A resin layer is formed on the first base board 1.
A positive type dry film or a negative type dry film can be employed as a
photosensitive dry film as explained in the paragraph (1). For example, a
preferably employable positive type dry film is such that it can be
dissolved in a developing liquid by irradiating active energy rays
thereto, while the negative dry film is prepared in the form of a
photo-polymerizable type negative film which can be dissolved or removable
peeled in a methylene chloride or a strong alkaline solution.
The positive type dry film is exemplified by "OZATEC R225" (trade name,
manufactured by Hoechst Japan Co. Ltd.), while the negative type dry film
is exemplified by "OZATEC T series" (trade name, manufactured by Hoechst
Japan Co., Ltd.), "PHOTOEC PET series" (trade name, manufactured by
Hitachi Kasei Kogyo Co., Ltd.) and "RISTON" (trade name, manufactured by
Dupont de Nemours Co., Ltd.). In addition to the foregoing commercial
products, it of course is obvious that a positively active resin compound,
e.g., a resin component containing naphkinon-diamide derivative and a
novolac type phenol resin as main components, negatively active resin
compound, e.g., a compound containing acrylorigomar having acrylester as
an reactive group, thermoplastic high molecular compound and a sensitizer
as main components, and a compound containing polyol, a polyethylene
compound and a sensitizer are also employable.
As a solvent soluble polymer as explained in the paragraph (2), any type of
high molecular compound is employable, provided that a solvent having the
foregoing polymer dissolved therein is available and a film can be formed
thereon by employing a coating process. A photoresist layer employable for
the solvent soluble polymer can typically be exemplified by a positive
type photoresist containing a novolac type phenol resin and
naphtokinon-diadid, a negative type liquid photoresist comprising a
polyvinylsinarmate, a negative type photoresist containing a cyclic rubber
and a bisadid, a negative type photosensitive dry film, a thermoses type
ink, and an ultraviolet ray setting type ink.
In addition, a material employable for forming the mold member 20 by
employing a printing process is exemplified by a flat plate ink, a screen
ink and a transferable type resin each of which is usable as a
vaporization drying type, a thermoses type or an ultraviolet ray setting
type.
Among a group of materials as mentioned above, it is preferable from the
viewpoint of a machining accuracy, ease of removal, an operational i
efficiency that means having a photosensitive dry film used therefor is
employed, and moreover, it is especially preferable from the same
viewpoint that means having a positive type dry film used therefor is
employed. Specifically, the positive type photosensitive material is most
preferably employable from the viewpoint of forming a number of liquid
paths 102, since it is superior to the negative type photosensitive
material in respect of resolution, and moreover, it has an advantageous
feature that a side wall surface of which relief pattern extends
vertically and smoothly or a sectional shape having a tapered type or a
reversely tapered type can easily be formed. Additionally, since the
positive type photosensitive material has another advantageous feature
that the relief pattern can removably be dissolved in a developing liquid
and an organic solvent, it is preferably employable as a material for
forming the mold member. Especially, since the positive type photoresist
including novolac type phenol resin and naphtokinon diadid as noted above
is completely dissolved in a weak alkaline aqueous solution or alcohol,
there does not arise a malfunction that each energy generating element
(ejection heater) 103 is injured or damaged therewith, and moreover, a
subsequent removing step can be achieved very quickly. Thus, a dry
film-shaped positive type photosensitive material having a film thickness
ranging from 10 .mu.m to 100 .mu.m can be noted as a most preferable
material.
Subsequently, after the mold member 20 is disposed or formed on the first
base board 1, a filling member 22 is laminated on the mold member 20 in
such a manner as to cover the mold member 20 therewith, and the filling
member 22 is filled in at least a concave portion of the mold member 20.
Any type of filling material is preferably employable, provided that the
mold member 20 can be covered therewith. Since the filling material is a
structural material employable for the liquid eject recording head 10
having number of liquid paths 102 and a liquid chamber 104 formed therein,
it is desirable to select the filling material having excellent
adhesiveness to the base board, a high mechanical strength, excellent
dimensional stability and excellent corrosion resistance. Materials each
hardenable when it is irradiated with active energy rays such as
ultraviolet rays, visual light beam, X-rays, infrared rays, electron beams
or the like while it is held liquid are suitably employable. Particularly,
they are exemplified by epoxy resin, acrylic resin, diglycol-dialkyl
carbonate resin, unsaturated polyester resin, polyurethane resin,
polyimido resin, melamine resin, phenol resin, and urea resin. Especially,
epoxy resin capable of starting to effect cation polymerization in receipt
of light beam, acryl oligomars each having an acrylic ester group capable
of starting to effect radical polymerization in receipt of light beam,
light additive polymerizable type resin having polyol and polyethylene
used therefor, and unsaturated cycloacethal resin are suitably employable
as structural materials for an ink jet recording head.
A method of ejecting a filling material from a plurality of nozzles
arranged corresponding to the contour of a base board, a method of
handling an applicator, a method of handling a curtain coater, a method of
handling a roll coater, a method of handling a spray coater and a method
of handling a spin coater can typically be noted as typical methods each
for laminating the filling member 22 on the mold member 20. In the case
that the mold member 22 is laminated with a liquid hardenable material, it
of course is obvious that the liquid hardenable material is deaerated
prior to lamination in order to avoid inclusion of gas bubbles in the
hardened laminated material.
FIG. 11A is an enlarged sectional view of the base board 1 filled with the
filling material 22 taken along a line 11A--11A in FIG. 10A, and FIG. 11B
is an enlarged sectional view of the same taken along a line 11B--11B in
FIG. 10A. The respective mold members 20 are dissolved at a subsequent
step so that they become cavities. The mold members 20 shown in FIG. 11A
become ink liquid paths 102. On the other hand, the mold members 20 shown
in FIG. 11B become communication paths 8 by way of which first grooves are
communicated with second grooves for forming an air chamber 7. Mold member
disposing portions 21 shown in FIG. 10 become columns 8B' between the
adjacent communication paths 8 at a step after they are filled by the
filling member 22.
Subsequently, a second base board 3 having two grooves formed therein is
connectably placed on the first base board 1. FIG. 10B is a plan view
which shows that the first base board and the second base board are
laminated one above another. A significant fact to be taken into account
is that a partition wall portion 13 between the two grooves are formed in
such a manner as to cover the concave portion 21 therewith. At this time,
the inner walls of the two groove on the first base board 1 have been
coated with a shading layer made of a material having light shading
capability against active energy rays effective for hardening the filled
member 22 as will be described later. A method of dipping the first base
board 1 in a shading layer solution so as to allow it to be coated
therewith, and thereafter, wiping off predetermined fixed parts such as
the concave portion 21 or the like and a method of adhering a masking tape
to parts on the first base board 1 having no shading layer required
thereon, and thereafter, dipping the first base board 1 so as to allow a
necessary part of the latter to be coated therewith can be noted as a
method to be advantageously employed for the purpose of forming a shading
layer. In addition, a metallic film spattering method, an etching method
or the like may be employed.
FIG. 12A is an enlarged sectional view of the first base board 1 and the
second base board 2 taken along a line 12A--12A in FIG. 10B, and FIG. 12B
is an enlarged sectional view of the first base board 1 and the second
base board 2 taken along a line 12B--12B in FIG. 10B. As is apparent from
these drawing, a shading layer 23 of the type as mentioned above is coated
only on the inner wall of two grooves 24 and 25 of the second base board
3. In the case that active energy rays are reliably irradiated from above
while maintaining the parallel relationship among them, it is acceptable
that only a ceiling portion of each of the grooves 24 and 25 is coated
with the shading layer 23. Incidentally, a portion which will later become
an ink liquid path 102, a portion which will later become the ejection
heater 103 and a portion which will later become the communication path 8
are included in the sectional plane extending along the line 12A--12A. On
the other hand, a portion which will later become the ink path 102, a
portion which will later become the ejection heater 103 and a portion
which will later become the column 8B are included in the sectional plane
extending along the line 12B--12B. When active energy rays 26 are
irradiated from above while maintaining the foregoing state, they invade
in a front wall, a partition wall and a rear wall so that the
photosensitive filled member 22 is hardened. As a result of the setting of
the photosensitive filled member 22, the bottom wall of a front wall 27,
the bottom wall of a partition wall 28 and the bottom wall of a rear wall
29 in the first base board 1 are adhesively connected to the second base
board 3 via the hardened solid layer 2.
Ultraviolet rays, visual light beam, X-rays, infrared rays, electron beams
can be utilized as active energy rays. In view of the fact that exposure
is achieved with the active energy rays 26 which have permeated through
the first base board 1, ultraviolet rays and visual light beam are
preferably employable. Among them, ultraviolet rays are most suitably
employable as active energy rays from the viewpoint of a polymerization
speed. Although processing can be achieved at a high accuracy when a power
source for generating few heat is used, any type of conventional light
source can be utilized, provided that it is practically used for the
purpose of producing a printing plate, handling a printed circuit or
hardening a photo-setting type paint.
After completion of the irradiation of the active energy rays 26, the mold
member 20 and an unhardened part of the filled member 22 are removed from
the laminated structure so that the state of the laminated structure shown
in FIGS. 12A and 12B is shifted to that shown in FIGS. 13A and 13B so as
to form the ink liquid path 102, the communication path 8 and the column
8B.
To remove the mold member 20 and the unhardened part of the filled member
22, it is desirable to employ a process of dipping the laminated structure
in a liquid capable of dissolving, expansibly swelling or peelably
removing them therefrom. Halogen-containing hydrocarbon, ketone, ester,
aromatic hydrocarbon, ether, alcohol, N-methylpyroridon, dimethyl
formaldehyde, phenol, water, acid-containing water or alkali-containing
water can be noted as means for removing the mold member 20 and the filled
member 22. A surface active agent may be added to each of the
aforementioned liquids as desired. In the case that a positive type dry
film is used as a mold member, it is preferable that ultraviolet rays are
additionally irradiated to the mold member to facilitate removable of the
latter. In the case that other materials rather than the positive type dry
film are used, it is preferable that they are heated to the temperature
range of 40.degree. to 60.degree. C.
As the mold member 20 and the unhardened part of the filled member 22 are
dipped and subjected to chemical treatment, they are dissolutely removed
from the ink ejection outlet 101, the ink feed port 30, the communication
path 8 and the two grooves 24 and 25.
If there is no need of forming the active energy ray shading layer 23, a
shading layer dissolving agent is additionally mixed with the foregoing
dissolving/dipping liquid, resulting in the number of steps being reduced.
It of course is obvious that the shading layer may be removed at a
different step.
On completion of the aforementioned steps, the opposite ends of the two
grooves in the laminated structure including the two base boards are
communicated with the outside. Thus, ink feed tube connecting members 9A
and 9B (see FIG. 1 and FIG. 2) are adhesively secured to the opposite ends
of the two grooves, whereby an ink jet recording head is completed. At
this time, to assure that the first groove 24, i.e., one of the two
grooves is communicated with the ink feed tubes 11A and 11B and the second
groove 25, i.e., the other one of the two grooves is sealably closed with
a part of each of the connecting members 9A and 9B, the contour of each of
the connecting members 9A and 9B is preliminarily designed so that the air
chamber 7 is formed. Thus, the second groove 25 sealably closed with the
connecting members 9A and 9B is communicated with the first groove 24
serving as a liquid chamber 104 only via the communication portion 8.
Accordingly, when ink is introduced into the liquid chamber 104, the other
region rather than the communication portion 8 aligned with the column 8B
serves as an air reservoir. At this time, since the communication portion
8 serves as a kind of ink reservoir, this makes it possible to prepare for
simultaneously eject ink from number of ink ejection outlets 101 at a high
speed.
Next, a method of producing an ink jet head according to another embodiment
of the present invention will be described below with reference to FIG. 14
to FIG. 18. In this embodiment, the method using more simply constructed
mold member and using more simple steps is described. These drawings show
the case that the method is applied to an ink jet head 20 shown in FIG. 7.
First, a mold member 20 is formed on a first base board 1 having a
plurality of ejection heaters 103, a heater driving circuit (not shown)
and others formed therein in the same manner as the preceding embodiment.
The mold member 20 is formed in the region positionally corresponding to a
common liquid chamber 104, a liquid path 102 and a communication path 8A
of a communication portion 8 as shown in FIG. 7, and a manner of forming
these components and materials employed for forming them are same as those
in the preceding embodiment. In the preceding embodiment, a column 8B is
built by forming the concave portion on the mold member 20. In contrast
with the preceding embodiment, in this embodiment, a comb-shaped mold
member is substituted for the concave portions.
Subsequently, after the mold member 20 is formed in that way, a filled
member layer 22 is formed on the mold member 20 in such a manner as to
cover the mold member 20 therewith as shown in FIG. 15 using an active
energy ray setting material such as an epoxy resin, an acrylic resin or
the like. After the filled member layer 22 is formed in that way, a second
base board 3 is laminated on the filled member layer 22 as shown in FIG.
16. It should be noted that a common liquid chamber 104 and an air chamber
7 are preliminarily formed in the second base board 3. In this embodiment,
after the second base board 3 is laminated in that way, photo-masks 21 are
adhesively placed on the second base board 3 as shown in FIG. 17 in the
regions located directly above the common liquid chamber 104 and the air
chamber 7 as shown in FIG. 17, and thereafter, active energy rays 26 are
irradiated toward the photo-masks 21 in the arrow-marked direction from
above.
In contrast with the preceding embodiment, since the photo-masks 21 are
employed in this embodiment, there is no need of forming shading layers in
a common liquid chamber and an air chamber. Thus, there arises a necessity
for taking into account as to how ink is adversely affected by the
material constituting the shading layers.
On completion of the irradiation of the active energy rays 26, only parts
22A and 22B of the filled member layer 22 positionally corresponding to
the air chamber 7 and the common liquid chamber 104 are left unhardened
but other part of the filled member layer 22 rather than the foregoing
parts 22A and 22B are hardened. Subsequently, as represented by the
arrow-marked directions in FIG. 18, the unhardened parts 22A and 22B of
the filled member layer 22 are dissolutely removed from other opening
portions of the common liquid chamber 104 and the air chamber 7 of which
opposite ends are kept open in the second base board 3. In addition, to
dissolutely remove the mold member 20, e.g., a halogen-containing
hydrocarbon is introduced into the second base board 3 so that the
dissolved part of the second base board 3 is discharged from the common
liquid chamber 104 and the air chamber 7, whereby the common liquid
chamber 104, the air chamber 7, the liquid paths 102 and the ink ejection
outlets 101 can simultaneously be formed together with the communication
portion 8.
As irradiation of the active energy rays 22 is performed in the
above-described manner, the active energy rays 22 permeate through the
filled member layer 22, causing the latter to be hardened. After
completion of the hardening of the filled member layer 22, the bottom
surface of a liquid path forming portion in the first base board 1, the
bottom wall of a wall between the common liquid chamber 104 and the air
chamber 7 and the bottom surface of a rear wall are adhesively connected
to the second base board 3 via the hardened solid layer 2 (serving as a
flow path forming member).
The same power source for irradiating the active energy ray 22 as that
employed in the preceding embodiment can likewise be used as a power
source for the same purpose.
After the laminated structure is built as shown in FIG. 18, the opposite
ends of the air chamber 7 are sealably closed with sealing members and ink
feed tubes 14A and 14B are fixedly secured to the opposite ends of the
common liquid chamber 104 via ink feed joints 9A and 9B in the same manner
as the preceding embodiment, whereby a desired ink jet head is obtained.
Here, the reason why a plurality of communication paths 8A are
concentratively arranged at the substantially central part of the ink jet
head as seen in the longitudinal direction will be described below.
Provided that a plurality of communication paths 8A are distributively
arranged in the longitudinal direction of the air chamber 7 as shown in
FIG. 19, when the common liquid chamber 104 is initially filled with ink
as represented by arrow-marked directions, a certain amount of ink invades
in the air chamber 7. This leads to the result that the air chamber 7
fails to exhibit a function as a buffer chamber. For this reason, it is
necessary that a part of or some part of the air chamber 7 is designed in
the form of a dead lane. To this end, in the case of an ink jet head as
shown in FIG. 5, the air chamber 7 is divided into several sections using
two partition members 12A so that communication paths 8A, 8B and 8C are
formed at the substantially central parts of air chamber segments 7A, 7B
and 7C. A method of producing an ink jet head of which air chamber 7 is
divided into two parts will briefly be described below with reference to
FIG. 20. A slit 31 is formed at the substantially central part of a second
base plate 3 having a first groove 24 and a second groove 25 formed
therein. It should be careful that the slit 31 does not extend in excess
of a partition wall 28 to reach the first groove 24. A slitting operation
is performed by actuating a rotary grinding wheel or operating a cutting
machine capable of accurately machining a material with the aid of a
rotary grinding wheel or a similar tool. A mold member 20 having a first
communication path forming portion 33 and a second communication path
forming portion 34 formed thereon is placed on a solid layer 2, and three
holes 21 are formed at both the communication path forming portions 33 and
34 in which columns 8B for a communication path 8 are later formed.
Subsequently, the communication path forming sections 33 and 34 are filled
with a photosensitive filling agent (not shown). A first base board 1 and
a second base board 3 are adhesively connected to each other by employing
the aforementioned process, and unnecessary parts are then dissolutely
removed from the laminated structure. Thereafter, a partition wall plate
30 is inserted into the slit 31 and then adhesively secured to the latter.
Finally, ink feed pipe connecting members 9A and 9B are adhesively
connected to the opposite ends of the second base board 2 by employing the
aforementioned process, whereby two air chambers can be formed with a
partition wall interposed therebetween. Thus, an ink jet head including
two ink storage and four air storage can be constructed. Incidentally,
each air chamber is communicated with the liquid chamber 104 via the
corresponding communication path. The present invention should not be
limited only to a single partition wall 30. Alternatively, two or more
partition walls 30 may be used so as to form air chambers more than the
aforementioned case. It of course is obvious that the number of
communication path forming portions varies correspondingly.
Next, a method of forming a plurality of partition members 11 in the case
that an air chamber 7 is divided into plural chambers with each partition
member 11 located between adjacent chambers for an ink jet head as shown
in FIG. 5 will be described below with reference to FIG. 21 to FIG. 23.
FIGS. 21A and 21B are views of an ink jet head which shows that two sealing
agent filling holes 24 each serving to form a partition member 11 are
preliminarily formed on a second base board 3 from above, and thereafter,
a sealing agent 23 is injected through each filling hole 24 to form the
partition wall 11 by solidifying the sealing agent 23. It should be noted
that each filling hole can be formed on the second base board 3 by
rotating a drill, irradiating a laser light beam or a supersonic jet
toward the filling hole or employing a blasting process.
Similarly, FIGS. 22A and 22B are views of an ink jet head which show that
two sealing agent filling holes 25 are formed in a second base board 3
from the rear side, and thereafter, a sealing agent 23 is injected through
each filling hole 25 to form a partition member with the solidified
sealing agent 23.
FIG. 23 is a fragmentary plan view of an ink jet head which shows the state
that a second base board 3 is laminated on a first base board 1 via a
solid layer 2 (see FIG. 18) wherein e.g., two elastic materials 27 are
squeezed from the opposite open ends of an air chamber 7 in the
arrow-marked direction to reach the position where two partition members
11 are formed with the elastic materials 27. Alternatively, squeezing
holes formed on the upper surface of the second base board 3 may be
substituted for the opposite open ends of the air chamber 7.
The present invention should not be limited only three air chambers defined
according to the first embodiment of the present invention. In addition, i
the present invention should not be limited to a single communication path
8A to be formed corresponding to individual air chamber. It of course is
possible to form a communication path similar to the communication paths
8A to 8C formed according to the first embodiment by additionally
employing the technique according to the second embodiment of the present
invention.
Next, a method of producing an ink jet head 30 shown in FIG. 8 will be
described below with reference to FIGS. 24A and 24B. In this case, to form
a mold member 20, the height of a communication path forming portion 20A
is dimensioned to be equal to the thickness of a filled member layer 22
formed at a step as shown in FIG. 24B. Thus, as shown in FIG. 24B, when
the filled member layer 22 is laminated on the mold member 20, the upper
surface of the communication path forming portion 20A can positionally be
coincident with the upper surface of the filled member layer 22.
Subsequently, the ink jet head 30 as shown in FIG. 8 can be obtained by
way of the aforementioned steps.
In addition, FIG. 25 and FIG. 26 show by way of example an ink jet head 40
and an ink jet head 50 each including a second base board 3 of which
structure is different from that constructed according to each of the
aforementioned embodiments. In the shown embodiment, the opposite ends of
a common liquid chamber 104 and an air chamber 7 formed in the second base
board 3 are not exposed to the outside in contrast with the aforementioned
embodiments. Therefore, in this embodiment, there does not arise a
necessity that opening portions on the opposite sides of the air chamber 7
are closed, and moreover, ink feed joints 9A and 9B are connected to
opening portions on the opposite ends of the common liquid chamber 104. In
FIG. 25, reference numeral 41 designates a hole. This hole 41 is formed in
the vicinity of the opposite ends of the common liquid chamber 104 and the
air chamber 7 at the upper portions of the both chamber so as to allow a
solvent and a dissolved part of the solid layer and the mold member 20 to
be discharged to the outside through the hole 41. In FIG. 26, reference
numeral 51 designates a hole which is formed on the first base board 1
side for the same purpose as that of the hole 41. According to this
embodiment, the ink jet heads 40 and 50 can be produced using the holes 41
and 51 by employing the aforementioned production method.
FIG. 27 shows by way of schematic perspective view a so-called full line
type recording head having a width corresponding to the recording width of
a recording medium such as a paper or the like and a recording apparatus
having a recording head of the foregoing type mounted thereon wherein
among a plurality of recording heads to each of which the present
invention is applicable, most remarkable advantages can be expected with
the foregoing recording head.
In FIG. 27, reference numeral 61 designates a full line recording head.
With the recording apparatus, ink is ejected from the recording head 61
toward a recording medium 80 such as a paper or the like so as to perform
a recording operation. Since there does not arise a malfunction that a
quality of recording is degraded with a long recording head like the full
line recording head, an article having a high quality of image recorded
thereon can be obtained with the recording head of the present invention.
FIG. 28 shows by way of perspective view the structure of a recording
apparatus having a small recording head mounted thereon. The recording
apparatus includes a carriage HC on which an ink tank portion 70 and a
recording head portion 60 are removably mounted. In addition, the
recording apparatus includes a motor 81 serving as a power source for
driving the carriage HC and rollers for conveying the recording medium 80,
and a carriage shaft 85 for transmitting the power from the power source
to the carriage HC. The apparatus further includes a signal supply means
(not shown) for supplying a signal to the ink jet head, whereby ink is
ejected from the ink jet head.
As is apparent from the above description, the ink jet head of the present
invention is employable for a recording apparatus as mentioned above. In
addition, it is preferably employable not only for an ink jet apparatus
including a signal receiving section for receiving an image signal from an
unit located outside of the recording apparatus and the ink jet head of
the present invention but also for an ink jet apparatus including a
treatment mechanism for carrying out pretreatment and post-treatment for
the purpose of ink fixing on a cloth and threads in addition to the
foregoing ink jet head.
As described above, the ink jet head of the present invention includes an
air chamber extending in parallel with the direction of arrangement of a
plurality of energy generating elements. With this construction, the air
chamber has a large volume enough to contain a large quantity of air
therein for absorbing ink vibration and pressure fluctuation in the air.
Consequently, the present invention can provide a so-called multi-nozzle
type ink jet head and an ink jet apparatus which assure that good and
quick refill can always be achieved by effectively utilizing the
advantages obtainable from the air chamber and that excellent high-speed
responsiveness and excellent ink ejection properties can be obtained
without any appearance of the problems associated with ink refilling for a
number of ink ejecting outlets.
According to the present invention, one of two grooves formed in a second
base board is used as an ink feeding chamber and other one of the two
grooves is used as an air chamber communicated with the ink feeding
chamber via communication paths while a part of the air chamber located
adjacent to the communication paths is used as an ink reservoir. With this
construction, when recording is achieved by quickly ejecting ink from all
the ink ejecting outlets, the ink reservoir serves to supplement ink
therefrom. Consequently, the present invention can contribute to actual
realization of an ink jet apparatus which assures a high quantity of
recording.
Since the communication portion is constructed according to each of the
aforementioned embodiments, ink vibration and pressure wave propagating in
the ink can effectively be absorbed. Also in the case that recording is
effected at a high speed, a high quality of recording can be assured.
With the method of producing an ink jet head according to the present
invention, communication paths and ink paths can be formed at a same step,
whereby an ink jet head constructed to exhibit the aforementioned
advantages can be produced by way of simple steps at an inexpensive cost
on the basis of mass production basis.
While the present invention has been described above with respect to
preferred embodiments thereof, it should of course be understood that the
present invention should not be limited only to these embodiments but
various change or modification may be made without any departure from the
scope of the present invention as defined by the appended claims.
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